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 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
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 * file and include the License file at packager/legal/LICENSE.txt.
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 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
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package javax.mail.internet;

import java.io.*;
import java.util.*;
import javax.mail.*;
import com.sun.mail.util.LineInputStream;
import com.sun.mail.util.PropUtil;

/**
 * InternetHeaders is a utility class that manages RFC822 style
 * headers. Given an RFC822 format message stream, it reads lines
 * until the blank line that indicates end of header. The input stream
 * is positioned at the start of the body. The lines are stored
 * within the object and can be extracted as either Strings or
 * {@link javax.mail.Header} objects.
 * <p>
 * 
 * This class is mostly intended for service providers. MimeMessage and MimeBody
 * use this class for holding their headers.
 * <p>
 * 
 * <hr>
 * <strong>A note on RFC822 and MIME headers</strong>
 * <p>
 * 
 * RFC822 and MIME header fields <strong>must</strong> contain only US-ASCII
 * characters. If a header contains non US-ASCII characters, it must be encoded
 * as per the rules in RFC 2047. The MimeUtility class provided in this package
 * can be used to to achieve this. Callers of the <code>setHeader</code>,
 * <code>addHeader</code>, and <code>addHeaderLine</code> methods are
 * responsible for enforcing the MIME requirements for the specified headers. In
 * addition, these header fields must be folded (wrapped) before being sent if
 * they exceed the line length limitation for the transport (1000 bytes for
 * SMTP). Received headers may have been folded. The application is responsible
 * for folding and unfolding headers as appropriate.
 * <p>
 * 
 * The current implementation supports the System property
 * <code>mail.mime.ignorewhitespacelines</code>, which if set to true will cause
 * a line containing only whitespace to be considered a blank line terminating
 * the header.
 * 
 * @see javax.mail.internet.MimeUtility
 * @author John Mani
 * @author Bill Shannon
 */

public class InternetHeaders {
	private static final boolean ignoreWhitespaceLines = PropUtil.getBooleanSystemProperty("mail.mime.ignorewhitespacelines", false);

	/**
	 * An individual internet header. This class is only used by
	 * subclasses of InternetHeaders.
	 * <p>
	 * 
	 * An InternetHeader object with a null value is used as a placeholder for
	 * headers of that name, to preserve the order of headers. A placeholder
	 * InternetHeader object with a name of ":" marks the location in the list
	 * of headers where new headers are added by default.
	 * 
	 * @since JavaMail 1.4
	 */
	protected static final class InternetHeader extends Header {
		/*
		 * Note that the value field from the superclass
		 * isn't used in this class. We extract the value
		 * from the line field as needed. We store the line
		 * rather than just the value to ensure that we can
		 * get back the exact original line, with the original
		 * whitespace, etc.
		 */
		String line; // the entire RFC822 header "line",

		// or null if placeholder

		/**
		 * Constructor that takes a line and splits out
		 * the header name.
		 */
		public InternetHeader(String l) {
			super("", ""); // XXX - we'll change it later
			int i = l.indexOf(':');
			if (i < 0) {
				// should never happen
				name = l.trim();
			} else {
				name = l.substring(0, i).trim();
			}
			line = l;
		}

		/**
		 * Constructor that takes a header name and value.
		 */
		public InternetHeader(String n, String v) {
			super(n, "");
			if (v != null)
				line = n + ": " + v;
			else
				line = null;
		}

		/**
		 * Return the "value" part of the header line.
		 */
		public String getValue() {
			int i = line.indexOf(':');
			if (i < 0)
				return line;
			// skip whitespace after ':'
			int j;
			for (j = i + 1; j < line.length(); j++) {
				char c = line.charAt(j);
				if (!(c == ' ' || c == '\t' || c == '\r' || c == '\n'))
					break;
			}
			return line.substring(j);
		}
	}

	/*
	 * The enumeration object used to enumerate an
	 * InternetHeaders object. Can return
	 * either a String or a Header object.
	 */
	static class matchEnum implements Enumeration {
		private Iterator e; // enum object of headers List
		// XXX - is this overkill? should we step through in index
		// order instead?
		private String names[]; // names to match, or not
		private boolean match; // return matching headers?
		private boolean want_line; // return header lines?
		private InternetHeader next_header; // the next header to be returned

		/*
		 * Constructor. Initialize the enumeration for the entire
		 * List of headers, the set of headers, whether to return
		 * matching or non-matching headers, and whether to return
		 * header lines or Header objects.
		 */
		matchEnum(List v, String n[], boolean m, boolean l) {
			e = v.iterator();
			names = n;
			match = m;
			want_line = l;
			next_header = null;
		}

		/*
		 * Any more elements in this enumeration?
		 */
		public boolean hasMoreElements() {
			// if necessary, prefetch the next matching header,
			// and remember it.
			if (next_header == null)
				next_header = nextMatch();
			return next_header != null;
		}

		/*
		 * Return the next element.
		 */
		public Object nextElement() {
			if (next_header == null)
				next_header = nextMatch();

			if (next_header == null)
				throw new NoSuchElementException("No more headers");

			InternetHeader h = next_header;
			next_header = null;
			if (want_line)
				return h.line;
			else
				return new Header(h.getName(), h.getValue());
		}

		/*
		 * Return the next Header object according to the match
		 * criteria, or null if none left.
		 */
		private InternetHeader nextMatch() {
			next:
			while (e.hasNext()) {
				InternetHeader h = (InternetHeader) e.next();

				// skip "place holder" headers
				if (h.line == null)
					continue;

				// if no names to match against, return appropriately
				if (names == null)
					return match ? null : h;

				// check whether this header matches any of the names
				for (int i = 0; i < names.length; i++) {
					if (names[i].equalsIgnoreCase(h.getName())) {
						if (match)
							return h;
						else
							// found a match, but we're
							// looking for non-matches.
							// try next header.
							continue next;
					}
				}
				// found no matches. if that's what we wanted, return it.
				if (!match)
					return h;
			}
			return null;
		}
	}

	/**
	 * The actual list of Headers, including placeholder entries.
	 * Placeholder entries are Headers with a null value and
	 * are never seen by clients of the InternetHeaders class.
	 * Placeholder entries are used to keep track of the preferred
	 * order of headers. Headers are never actually removed from
	 * the list, they're converted into placeholder entries.
	 * New headers are added after existing headers of the same name
	 * (or before in the case of <code>Received</code> and
	 * <code>Return-Path</code> headers). If no existing header
	 * or placeholder for the header is found, new headers are
	 * added after the special placeholder with the name ":".
	 * 
	 * @since JavaMail 1.4
	 */
	protected List headers;

	/**
	 * Create an empty InternetHeaders object. Placeholder entries
	 * are inserted to indicate the preferred order of headers.
	 */
	public InternetHeaders() {
		headers = new ArrayList(40);
		headers.add(new InternetHeader("Return-Path", null));
		headers.add(new InternetHeader("Received", null));
		headers.add(new InternetHeader("Resent-Date", null));
		headers.add(new InternetHeader("Resent-From", null));
		headers.add(new InternetHeader("Resent-Sender", null));
		headers.add(new InternetHeader("Resent-To", null));
		headers.add(new InternetHeader("Resent-Cc", null));
		headers.add(new InternetHeader("Resent-Bcc", null));
		headers.add(new InternetHeader("Resent-Message-Id", null));
		headers.add(new InternetHeader("Date", null));
		headers.add(new InternetHeader("From", null));
		headers.add(new InternetHeader("Sender", null));
		headers.add(new InternetHeader("Reply-To", null));
		headers.add(new InternetHeader("To", null));
		headers.add(new InternetHeader("Cc", null));
		headers.add(new InternetHeader("Bcc", null));
		headers.add(new InternetHeader("Message-Id", null));
		headers.add(new InternetHeader("In-Reply-To", null));
		headers.add(new InternetHeader("References", null));
		headers.add(new InternetHeader("Subject", null));
		headers.add(new InternetHeader("Comments", null));
		headers.add(new InternetHeader("Keywords", null));
		headers.add(new InternetHeader("Errors-To", null));
		headers.add(new InternetHeader("MIME-Version", null));
		headers.add(new InternetHeader("Content-Type", null));
		headers.add(new InternetHeader("Content-Transfer-Encoding", null));
		headers.add(new InternetHeader("Content-MD5", null));
		headers.add(new InternetHeader(":", null));
		headers.add(new InternetHeader("Content-Length", null));
		headers.add(new InternetHeader("Status", null));
	}

	/**
	 * Read and parse the given RFC822 message stream till the
	 * blank line separating the header from the body. The input
	 * stream is left positioned at the start of the body. The
	 * header lines are stored internally.
	 * <p>
	 * 
	 * For efficiency, wrap a BufferedInputStream around the actual input stream
	 * and pass it as the parameter.
	 * <p>
	 * 
	 * No placeholder entries are inserted; the original order of the headers is
	 * preserved.
	 * 
	 * @param is
	 *            RFC822 input stream
	 */
	public InternetHeaders(InputStream is) throws MessagingException {
		headers = new ArrayList(40);
		load(is);
	}

	/**
	 * Read and parse the given RFC822 message stream till the
	 * blank line separating the header from the body. Store the
	 * header lines inside this InternetHeaders object. The order
	 * of header lines is preserved.
	 * <p>
	 * 
	 * Note that the header lines are added into this InternetHeaders object, so
	 * any existing headers in this object will not be affected. Headers are
	 * added to the end of the existing list of headers, in order.
	 * 
	 * @param is
	 *            RFC822 input stream
	 */
	public void load(InputStream is) throws MessagingException {
		// Read header lines until a blank line. It is valid
		// to have BodyParts with no header lines.
		String line;
		LineInputStream lis = new LineInputStream(is);
		String prevline = null; // the previous header line, as a string
		// a buffer to accumulate the header in, when we know it's needed
		StringBuffer lineBuffer = new StringBuffer();

		try {
			// while ((line = lis.readLine()) != null) {
			do {
				line = lis.readLine();
				if (line != null && (line.startsWith(" ") || line.startsWith("\t"))) {
					// continuation of header
					if (prevline != null) {
						lineBuffer.append(prevline);
						prevline = null;
					}
					lineBuffer.append("\r\n");
					lineBuffer.append(line);
				} else {
					// new header
					if (prevline != null)
						addHeaderLine(prevline);
					else if (lineBuffer.length() > 0) {
						// store previous header first
						addHeaderLine(lineBuffer.toString());
						lineBuffer.setLength(0);
					}
					prevline = line;
				}
			} while (line != null && !isEmpty(line));
		} catch (IOException ioex) {
			throw new MessagingException("Error in input stream", ioex);
		}
	}

	/**
	 * Is this line an empty (blank) line?
	 */
	private static final boolean isEmpty(String line) {
		return line.length() == 0 || (ignoreWhitespaceLines && line.trim().length() == 0);
	}

	/**
	 * Return all the values for the specified header. The
	 * values are String objects. Returns <code>null</code> if no headers with
	 * the specified name exist.
	 * 
	 * @param name
	 *            header name
	 * @return array of header values, or null if none
	 */
	public String[] getHeader(String name) {
		Iterator e = headers.iterator();
		// XXX - should we just step through in index order?
		List v = new ArrayList(); // accumulate return values

		while (e.hasNext()) {
			InternetHeader h = (InternetHeader) e.next();
			if (name.equalsIgnoreCase(h.getName()) && h.line != null) {
				v.add(h.getValue());
			}
		}
		if (v.size() == 0)
			return (null);
		// convert List to an array for return
		String r[] = new String[v.size()];
		r = (String[]) v.toArray(r);
		return (r);
	}

	/**
	 * Get all the headers for this header name, returned as a single
	 * String, with headers separated by the delimiter. If the
	 * delimiter is <code>null</code>, only the first header is
	 * returned. Returns <code>null</code> if no headers with the specified name
	 * exist.
	 * 
	 * @param name
	 *            header name
	 * @param delimiter
	 *            delimiter
	 * @return the value fields for all headers with
	 *         this name, or null if none
	 */
	public String getHeader(String name, String delimiter) {
		String s[] = getHeader(name);

		if (s == null)
			return null;

		if ((s.length == 1) || delimiter == null)
			return s[0];

		StringBuffer r = new StringBuffer(s[0]);
		for (int i = 1; i < s.length; i++) {
			r.append(delimiter);
			r.append(s[i]);
		}
		return r.toString();
	}

	/**
	 * Change the first header line that matches name
	 * to have value, adding a new header if no existing header
	 * matches. Remove all matching headers but the first.
	 * <p>
	 * 
	 * Note that RFC822 headers can only contain US-ASCII characters
	 * 
	 * @param name
	 *            header name
	 * @param value
	 *            header value
	 */
	public void setHeader(String name, String value) {
		boolean found = false;

		for (int i = 0; i < headers.size(); i++) {
			InternetHeader h = (InternetHeader) headers.get(i);
			if (name.equalsIgnoreCase(h.getName())) {
				if (!found) {
					int j;
					if (h.line != null && (j = h.line.indexOf(':')) >= 0) {
						h.line = h.line.substring(0, j + 1) + " " + value;
						// preserves capitalization, spacing
					} else {
						h.line = name + ": " + value;
					}
					found = true;
				} else {
					headers.remove(i);
					i--; // have to look at i again
				}
			}
		}

		if (!found) {
			addHeader(name, value);
		}
	}

	/**
	 * Add a header with the specified name and value to the header list.
	 * <p>
	 * 
	 * The current implementation knows about the preferred order of most
	 * well-known headers and will insert headers in that order. In addition, it
	 * knows that <code>Received</code> headers should be inserted in reverse
	 * order (newest before oldest), and that they should appear at the
	 * beginning of the headers, preceeded only by a possible
	 * <code>Return-Path</code> header.
	 * <p>
	 * 
	 * Note that RFC822 headers can only contain US-ASCII characters.
	 * 
	 * @param name
	 *            header name
	 * @param value
	 *            header value
	 */
	public void addHeader(String name, String value) {
		int pos = headers.size();
		boolean addReverse = name.equalsIgnoreCase("Received") || name.equalsIgnoreCase("Return-Path");
		if (addReverse)
			pos = 0;
		for (int i = headers.size() - 1; i >= 0; i--) {
			InternetHeader h = (InternetHeader) headers.get(i);
			if (name.equalsIgnoreCase(h.getName())) {
				if (addReverse) {
					pos = i;
				} else {
					headers.add(i + 1, new InternetHeader(name, value));
					return;
				}
			}
			// marker for default place to add new headers
			if (!addReverse && h.getName().equals(":"))
				pos = i;
		}
		headers.add(pos, new InternetHeader(name, value));
	}

	/**
	 * Remove all header entries that match the given name
	 * 
	 * @param name
	 *            header name
	 */
	public void removeHeader(String name) {
		for (int i = 0; i < headers.size(); i++) {
			InternetHeader h = (InternetHeader) headers.get(i);
			if (name.equalsIgnoreCase(h.getName())) {
				h.line = null;
				// headers.remove(i);
				// i--; // have to look at i again
			}
		}
	}

	/**
	 * Return true if header exists
	 * 
	 * @param name
	 */
	public boolean hasHeader(String name) {
		for (int i = 0; i < headers.size(); i++) {
			InternetHeader h = (InternetHeader) headers.get(i);
			if (name.equalsIgnoreCase(h.getName())) {
				return true;
			}
		}
		return false;
	}
	
	/**
	 * Return all the headers as an Enumeration of {@link javax.mail.Header}
	 * objects.
	 * 
	 * @return Header objects
	 */
	public Enumeration getAllHeaders() {
		return (new matchEnum(headers, null, false, false));
	}

	/**
	 * Return all matching {@link javax.mail.Header} objects.
	 * 
	 * @return matching Header objects
	 */
	public Enumeration getMatchingHeaders(String[] names) {
		return (new matchEnum(headers, names, true, false));
	}

	/**
	 * Return all non-matching {@link javax.mail.Header} objects.
	 * 
	 * @return non-matching Header objects
	 */
	public Enumeration getNonMatchingHeaders(String[] names) {
		return (new matchEnum(headers, names, false, false));
	}

	/**
	 * Add an RFC822 header line to the header store.
	 * If the line starts with a space or tab (a continuation line),
	 * add it to the last header line in the list. Otherwise,
	 * append the new header line to the list.
	 * <p>
	 * 
	 * Note that RFC822 headers can only contain US-ASCII characters
	 * 
	 * @param line
	 *            raw RFC822 header line
	 */
	public void addHeaderLine(String line) {
		try {
			char c = line.charAt(0);
			if (c == ' ' || c == '\t') {
				InternetHeader h = (InternetHeader) headers.get(headers.size() - 1);
				h.line += "\r\n" + line;
			} else
				headers.add(new InternetHeader(line));
		} catch (StringIndexOutOfBoundsException e) {
			// line is empty, ignore it
			return;
		} catch (NoSuchElementException e) {
			// XXX - vector is empty?
		}
	}

	/**
	 * Return all the header lines as an Enumeration of Strings.
	 */
	public Enumeration getAllHeaderLines() {
		return (getNonMatchingHeaderLines(null));
	}

	/**
	 * Return all matching header lines as an Enumeration of Strings.
	 */
	public Enumeration getMatchingHeaderLines(String[] names) {
		return (new matchEnum(headers, names, true, true));
	}

	/**
	 * Return all non-matching header lines
	 */
	public Enumeration getNonMatchingHeaderLines(String[] names) {
		return (new matchEnum(headers, names, false, true));
	}
}
